Polyisocyanurate foams are well known, and are described for example in U.S. Pat. Nos. 3,903,346; 3,940,517; and 4,028,158 and United Kingdom Specification No. 1,433,641. German Offenlegungsschrift No. 2,546,183 published July 1, 1976, reportedly corresponding to U.S. Application Ser. No. 534,559 filed Dec. 19, 1974 relates to the production of polyisocyanurate foams employing furfuryl alcohol.
However, many such polyisocyanurate foams exhibit an undesirably high friability. This high friability results in a foam that is dusty, and which has low compressive strength and low tensile strength.
Furthermore, many prior polyisocyanurate foams suffer from a lack of structural integrity when exposed to fire. Although all such polyisocyanurate foams burn to a certain extent, it is highly desirable that the fully burned foam maintain its structural integrity in order to inhibit flame propagation and in order to pass certain standards.
Accordingly, it is an object of the present invention to provide an improved polyisocyanurate foam having a reduced friability.
Another object of the present invention is to provide an improved polyisocyanurate foam that maintains its structural integrity when it burns. Another object is to provide a process for producing an improved polyisocyanurate foam. Additional objects and advantages of the present invention will be apparent to those skilled in the art by reference to the following detailed description.